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OCR Biology A
22 Cloning and biotechnology
Teacher notes
Cloning and biotechnology
Specification references

6.1.3

6.2.1
Introduction
This task is linked with applying students’ knowledge of DNA sequencing and cloning. One
possible application of this knowledge may be to sequence the DNA found in fossils of very rare
species. This could make it possible to increase a rare population using cloning or even to
resurrect an extinct species. The task focuses on the question of whether it might be possible to
clone a woolly mammoth. It ends with a consideration of the ethical issues surrounding this area
of biology.
Learning outcomes
After completing the worksheet students should be able to:

review knowledge of DNA sequencing techniques

apply knowledge of genetic modification and cloning techniques

explore the moral issues surrounding GM and cloning research.
Teacher notes

Students need to distinguish reproductive from non-reproductive cloning. An interesting area
for further investigation lies in the theory of telomere shortening and its link with aging.

In the ethical arguments, students should be precise, e.g. a clear example rather than simply
ethical problems of animal welfare. Students need to compare both sides of an ethical
discussion and show reasoned arguments in support of the points made. They may hold
strong personal views, which can be defended in their arguments. Students need to be
careful not to allow personal beliefs to bias the discussion of both points of view.

Students might like to consider the role of endonucleases in living bacteria. This could be
linked with a research project linking enzyme specificity with anti-viral defence systems in
bacteria. The question of how bacterial DNA can be protected from the action of these
enzymes could then link with wider consideration of the use of chemicals binding to DNA to
control transcription, such as in operon action.

This could lead to a discussion of the moral issues of resurrecting an extinct species or the
use of cloning to preserve very rare species. The desirability of avoiding extinction could be
weighed against the potential for genetic weakness due to lack of variation. A case study
could be the cheetah. This then links with the study of evolution and population bottlenecks
(section 6.1.2).
Answers
1 a Attach a primer to the unknown sequence
Use DNA polymerase to make a complementary strand
Supply, modified/dideoxy, nucleotides tagged with coloured fluorescent markers as well
as normal nucleotides
One different colour per base
DNA polymerase stops replicating when a modified nucleotide is used
(1 mark)
(1 mark)
(1 mark)
(1 mark)
(1 mark)
© Oxford University Press 2016 http://www.oxfordsecondary.co.uk/acknowledgements
This resource sheet may have been changed from the original
1
OCR Biology A
22 Cloning and biotechnology
Teacher notes
Produces strands of different lengths
Separate the strands by electrophoresis
Strands will be colour coded according to the bases
Strands will be separated according to length
Read the order of the bases from the coloured tags
(1 mark)
(1 mark)
(1 mark)
(1 mark)
(1 mark)
(Max 4 marks)
b From bacteria/fungi/decomposers/humans who excavated the mammoth
2 a Mammoth DNA may be incomplete/damaged
Only certain genes can be sequenced
Only certain genes can be identified
b Active site matches specific base sequence
Often recognise a palindromic site
Cut the sugar-phosphate backbone
May leave sticky ends
(1 mark)
(1 mark)
(1 mark)
(1 mark)
(Max 2 marks)
(1 mark)
(1 mark)
(1 mark)
(1 mark)
(Max 2 marks)
c Cut non-coding parts of the host DNA
Cut Introns
d Gene database could be used
Allows quick comparison of the mammoth and elephant gene sequences
Identifies genes common to mammoth and other animals
Could allow function of mammoth gene sequences to be predicted
(1 mark)
(1 mark)
(Max 1 mark)
(1 mark)
(1 mark)
(1 mark)
(1 mark)
(Max 3 marks)
3 a Remove the nucleus from an elephant egg
Transfer the modified nucleus into an enucleated elephant egg
Allow cell division to form an embryo
Transfer the embryo into a surrogate mother/female elephant
b SCNT/Artificial cloning of animals
(1 mark)
(1 mark)
(1 mark)
(1 mark)
(4 marks)
(1 mark)
4 For
Could save/multiply, rare animals
Could multiply high value animals
Could multiply genetically modified animals that have a specific attribute; e.g. the ability to make a
pharmaceutical chemical in milk
Can generate STEM cells for therapeutic processes
© Oxford University Press 2016 http://www.oxfordsecondary.co.uk/acknowledgements
This resource sheet may have been changed from the original
2
OCR Biology A
22 Cloning and biotechnology
Teacher notes
Against
Description of how animal welfare might be compromised
Loss of genetic variety increases vulnerability to selection/environmental change/disease
Doubt about the health of the cloned animal
Doubt about the lifespan of the cloned animal
1–2 marks
Students restrict their answers to one or two comparative points. Little or no discussion of the ethical points.
One sided responses.
3–4 marks
At least two points made for each side of the argument with some discussion of the ethical points
5–6 marks
A range of points for each side of the argument, together with a reasoned evaluation of the two sides of the
argument. There may also be a view held and defended by the candidate.
(6 marks)
© Oxford University Press 2016 http://www.oxfordsecondary.co.uk/acknowledgements
This resource sheet may have been changed from the original
3